Hybrid vehicles are described, for example, in German Published Patent Application No. 102 03 760, which discloses a method for adjusting a setpoint operating state of a hybrid vehicle, in which an internal combustion engine is mechanically coupled to two electric motors.
In such hybrid vehicles, a negative drive torque which is necessary to decelerate the vehicle is generated jointly by an internal combustion engine, one or more electric motors, and possibly a hydraulic brake. The objective is to minimize use of the hydraulic brake, and to provide the main portion of the negative drive torque by combining the internal combustion engine and one or more electric motors. The portion provided by the combination of the internal combustion engine and electric motor(s) is referred to below as the drivetrain torque. The portion provided by the electric motors is used to generate electrical power, which is stored in a battery. In conventional HEVs the fuel injection into the internal combustion engine is also suppressed to conserve fuel (overrun mode). In this case the drag torque of the internal combustion engine contributes to the negative drivetrain torque.